1. Field of the Invention
The present invention relates generally to filtering devices. In particular, the present invention relates to a renewable spin-on type filter including a high strength plastic housing.
2. Discussion of Background
Spin-on, twist-on type filters are used in numerous liquid and pneumatic applications throughout the agricultural, mobile, commercial and industrial markets. The housing or can for most spin-on disposable filters are manufactured by deep-draw forming of malleable materials such as aluminum. This technique limits the structural capabilities of current spin-on and twist-on type disposable products to the production capabilities of the metal forming industry and to the molecular characteristics of a limited number of specific malleable metals. Prior art disposable filters use a stamped steel or cast cover plate to secure the housing or can to a mounting and distribution head assembly. This plate typically has a threaded center hole and is spot welded and/or crimp sealed to a deep-drawn can. The purpose of the cover plate is to provide a mounting site that contains sufficient strength to allow operation of the filter at the required pressure rating. These prior art techniques for sealing and connecting the can to the plate, plus the structural limits of thin gauge malleable metals, restrict the application and uses of prior art spin-on, twist-on disposable filters. Recently new high pressure, high burst strength disposable filter housings with burst pressure ratings in the 1000 psi range have been developed for some narrowly defined markets and applications. However, even these newer high-strength filters remain applicationally limited because of their continued use of deep-drawn metal cans.
The filter media used in the prior art are usually paper products that are flexible and flimsy. As a result of their flexible and flimsy characteristics these filters often are not properly secured in place within the housing or can during the assembly of the filter. By some accounts 50% of current commercially available oil filters are defective and thus do not perform up to specification. Also, prior art paper filters often develop rips or tears during use. Such defects are not visible and the filter is used for its normal use period during which improperly filtered oil is re-circulated through the engine. Serious damage to the engine can result.
Once these disposable filters have served their purpose and are in need of replacement, the filter is removed from the vehicle or machine and the remaining filtrate, usually oil, is drained and replaced. Thereafter, the filter is compacted and disposed of in accordance with industry practice. The impact on the environment from the disposal of used filters and oil cannot be overstated when the variety of industrial and consumer applications that employ disposable filters, as well as the frequency with which they are replaced, is considered. The enormity of this situation and its impact on the environment can be appreciated when it is realized that there are currently about 180,000,000 vehicles in the United States for which it is recommend that the filter and oil be change every 3,000 miles. About 400,000,000 oil filters are manufactured in the U.S. each year, of which less than 25% are properly recycled. The remaining, which retain some oil, are disposed of and this used oil enters the environment. Even properly drained oil filters retain up to 8 ounces of used oil. It is estimated that the result of recycling would result in the recovery of more than 17,000,000 gallons of oil. If properly processed this oil could be reused.
Therefore, there exists a need for a twist-on filter that is renewable, which would support and encourage the recycling of used oil and reduce environmental liability.